doc: improve table accessibility

The compatibility matrix in the N-API doc needs row headers for
accessibility purposes. Unfortunately, those aren't possible in markdown
without resorting to HTML markup. So this converts the table from
markdown to HTML. This is less convenient for documentation authors and
for other readers of the raw markdown docs, but I believe accessibility
for the viewers of our HTML docs outweighs that concern.

PR-URL: #35146
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Derek Lewis <DerekNonGeneric@inf.is>
Reviewed-By: Zeyu Yang <himself65@outlook.com>

Author: Trott

doc/api/n-api.md

@@ -244,16 +244,92 @@ from version 3 with some additions. This means that it is not necessary
 to recompile for new versions of Node.js which are
 listed as supporting a later version.
 
-|       | 1        | 2        | 3        | 4        | 5         | 6         |
-|-------|----------|----------|----------|----------|-----------|-----------|
-| v6.x  |          |          | v6.14.2* |          |           |           |
-| v8.x  | v8.6.0** | v8.10.0* | v8.11.2  | v8.16.0  |           |           |
-| v9.x  | v9.0.0*  | v9.3.0*  | v9.11.0* |          |           |           |
-| v10.x | v10.0.0  | v10.0.0  | v10.0.0  | v10.16.0 | v10.17.0  | v10.20.0  |
-| v11.x | v11.0.0  | v11.0.0  | v11.0.0  | v11.8.0  |           |           |
-| v12.x | v12.0.0  | v12.0.0  | v12.0.0  | v12.0.0  | v12.11.0  | v12.17.0  |
-| v13.x | v13.0.0  | v13.0.0  | v13.0.0  | v13.0.0  | v13.0.0   |           |
-| v14.x | v14.0.0  | v14.0.0  | v14.0.0  | v14.0.0  | v14.0.0   | v14.0.0   |
+<!-- For accessibility purposes, this table needs row headers. That means we
+     can't do it in markdown. Hence, the raw HTML. -->
+
+<table>
+  <tr>
+    <td></td>
+    <th scope="col">1</th>
+    <th scope="col">2</th>
+    <th scope="col">3</th>
+    <th scope="col">4</th>
+    <th scope="col">5</th>
+    <th scope="col">6</th>
+  </tr>
+  <tr>
+    <th scope="row">v6.x</th>
+    <td></td>
+    <td></td>
+    <td>v6.14.2*</td>
+    <td></td>
+    <td></td>
+    <td></td>
+  </tr>
+  <tr>
+    <th scope="row">v8.x</th>
+    <td>v8.6.0**</td>
+    <td>v8.10.0*</td>
+    <td>v8.11.2</td>
+    <td>v8.16.0</td>
+    <td></td>
+    <td></td>
+  </tr>
+  <tr>
+    <th scope="row">v9.x</th>
+    <td>v9.0.0*</td>
+    <td>v9.3.0*</td>
+    <td>v9.11.0*</td>
+    <td></td>
+    <td></td>
+    <td></td>
+  </tr>
+  <tr>
+    <th scope="row">v10.x</th>
+    <td>v10.0.0</td>
+    <td>v10.0.0</td>
+    <td>v10.0.0</td>
+    <td>v10.16.0</td>
+    <td>v10.17.0</td>
+    <td>v10.20.0</td>
+  </tr>
+  <tr>
+    <th scope="row">v11.x</th>
+    <td>v11.0.0</td>
+    <td>v11.0.0</td>
+    <td>v11.0.0</td>
+    <td>v11.8.0</td>
+    <td></td>
+    <td></td>
+  </tr>
+  <tr>
+    <th scope="row">v12.x</th>
+    <td>v12.0.0</td>
+    <td>v12.0.0</td>
+    <td>v12.0.0</td>
+    <td>v12.0.0</td>
+    <td>v12.11.0</td>
+    <td>v12.17.0</td>
+  </tr>
+  <tr>
+    <th scope="row">v13.x</th>
+    <td>v13.0.0</td>
+    <td>v13.0.0</td>
+    <td>v13.0.0</td>
+    <td>v13.0.0</td>
+    <td>v13.0.0</td>
+    <td></td>
+  </tr>
+  <tr>
+    <th scope="row">v14.x</th>
+    <td>v14.0.0</td>
+    <td>v14.0.0</td>
+    <td>v14.0.0</td>
+    <td>v14.0.0</td>
+    <td>v14.0.0</td>
+    <td>v14.0.0</td>
+  </tr>
+</table>
 
 \* N-API was experimental.